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Full text of "Text Book Of Mechanical Engineering"


294                  Plate-edge Planing Mac/line.

previously described. A fixed ram N on the top of the
framing, has a cylinder M in the- form of a girder, to which a
constant water pressure is supplied, and the girder is connected
by bolts to the beam B, so that a rise of the latter takes place
whenever the main cylinder is opened to exhaust. The angle
bar p prevents the plate from lifting, and L is a stop valve.

A Plate-edge Planing Machine is shewn at Fig. 285,
having a long table A, upon which the plate is clamped by
screws B B. The tool c is fixed in a cylindrical box, provided
with handle r> resting on stops, so that direction of tool point may
be reversed at either end of cut, shewn by the arc E j this is
performed by the workman, who travels on a platform F attached
to the saddle v. The latter has a hand-wheel and screw G to
set the tool, while the wheel H, turned by hand, gives vertical
feed. The saddle is traversed by screw j, driven from the
countershaft K by gearing: while K is provided with fast pullies
M, N) and loose pullies L L L. When the forks are in the position
shewn, no work is done, but if the straps (crossed and open)
be moved to the right the saddle will travel to the left and
vice versd. Reversal is automatically effected by projections
p p striking the stops Q Q at either end of the stroke alternately,
thus moving the straps, decision being given by the weight R,
which causes a pressure between the rollers at s. The mid
position is fixed by stops T : and the standards are so arranged
at u that they overhang the work, thus allowing the admission of
any length of plate. One setting may serve for several plates.

A Band Sawing Machine is a very useful tool in a boiler
shop for cutting out plates of intricate shape, while straight plates,
too thick to be sheared or punched, are cut by a circular saw
^rhen necessary. As these are so well-known in their wood-
working capacity, diagrams have been thought unnecessary,
v Plate-Bending Rolls, in their most common form, are
shewn in Figs. 286 and 287, the rollers being supported hori-
zontally. These are the design of Mr. John Cochrane, of
Barrhead The lower rolls A A revolve in fixed bearings, while
those of the upper roll B are lifted or lowered by the screw c, the
worm wheel D acting as a nut, while the worm is turned by the
spoked wheel E, A A are the driving rolls, and the gearing ig very